diff --git a/proxy/shadowsocks/ota.go b/proxy/shadowsocks/ota.go
index ede922fa..3613d639 100644
--- a/proxy/shadowsocks/ota.go
+++ b/proxy/shadowsocks/ota.go
@@ -4,12 +4,10 @@ import (
 	"bytes"
 	"crypto/hmac"
 	"crypto/sha1"
+	"errors"
 	"io"
-
 	"v2ray.com/core/common/alloc"
-	"v2ray.com/core/common/log"
 	"v2ray.com/core/common/serial"
-	"v2ray.com/core/transport"
 )
 
 const (
@@ -98,8 +96,7 @@ func (this *ChunkReader) Read() (*alloc.Buffer, error) {
 	actualAuthBytes := this.auth.Authenticate(nil, payload)
 	if !bytes.Equal(authBytes, actualAuthBytes) {
 		buffer.Release()
-		log.Debug("AuthenticationReader: Unexpected auth: ", authBytes)
-		return nil, transport.ErrCorruptedPacket
+		return nil, errors.New("Shadowsocks|AuthenticationReader: Invalid auth.")
 	}
 	buffer.SliceFrom(AuthSize)
 
diff --git a/proxy/socks/protocol/socks.go b/proxy/socks/protocol/socks.go
index 847764c8..ee81684a 100644
--- a/proxy/socks/protocol/socks.go
+++ b/proxy/socks/protocol/socks.go
@@ -1,13 +1,13 @@
 package protocol
 
 import (
+	"errors"
+	"fmt"
 	"io"
-
 	"v2ray.com/core/common/alloc"
 	"v2ray.com/core/common/log"
 	v2net "v2ray.com/core/common/net"
 	"v2ray.com/core/proxy"
-	"v2ray.com/core/transport"
 )
 
 const (
@@ -47,8 +47,7 @@ func ReadAuthentication(reader io.Reader) (auth Socks5AuthenticationRequest, aut
 		return
 	}
 	if nBytes < 2 {
-		log.Warning("Socks: expected 2 bytes read, but only ", nBytes, " bytes read")
-		err = transport.ErrCorruptedPacket
+		err = errors.New("Socks: Insufficient header.")
 		return
 	}
 
@@ -224,8 +223,7 @@ func ReadRequest(reader io.Reader) (request *Socks5Request, err error) {
 			return
 		}
 	default:
-		log.Warning("Socks: Unexpected address type ", request.AddrType)
-		err = transport.ErrCorruptedPacket
+		err = fmt.Errorf("Socks: Unexpected address type %d", request.AddrType)
 		return
 	}
 
diff --git a/proxy/socks/protocol/socks_test.go b/proxy/socks/protocol/socks_test.go
index 0f12b19d..c61983f0 100644
--- a/proxy/socks/protocol/socks_test.go
+++ b/proxy/socks/protocol/socks_test.go
@@ -9,7 +9,6 @@ import (
 	v2net "v2ray.com/core/common/net"
 	"v2ray.com/core/proxy"
 	"v2ray.com/core/testing/assert"
-	"v2ray.com/core/transport"
 )
 
 func TestHasAuthenticationMethod(t *testing.T) {
@@ -136,7 +135,7 @@ func TestSingleByteAuthRequest(t *testing.T) {
 	assert := assert.On(t)
 
 	_, _, err := ReadAuthentication(bytes.NewReader(make([]byte, 1)))
-	assert.Error(err).Equals(transport.ErrCorruptedPacket)
+	assert.Error(err).IsNotNil()
 }
 
 func TestZeroAuthenticationMethod(t *testing.T) {
diff --git a/proxy/socks/protocol/udp.go b/proxy/socks/protocol/udp.go
index 6c01571e..9fd05339 100644
--- a/proxy/socks/protocol/udp.go
+++ b/proxy/socks/protocol/udp.go
@@ -2,11 +2,9 @@ package protocol
 
 import (
 	"errors"
-
+	"fmt"
 	"v2ray.com/core/common/alloc"
-	"v2ray.com/core/common/log"
 	v2net "v2ray.com/core/common/net"
-	"v2ray.com/core/transport"
 )
 
 var (
@@ -40,7 +38,7 @@ func (request *Socks5UDPRequest) Write(buffer *alloc.Buffer) {
 
 func ReadUDPRequest(packet []byte) (*Socks5UDPRequest, error) {
 	if len(packet) < 5 {
-		return nil, transport.ErrCorruptedPacket
+		return nil, errors.New("Socks|UDP: Insufficient length of packet.")
 	}
 	request := new(Socks5UDPRequest)
 
@@ -53,7 +51,7 @@ func ReadUDPRequest(packet []byte) (*Socks5UDPRequest, error) {
 	switch addrType {
 	case AddrTypeIPv4:
 		if len(packet) < 10 {
-			return nil, transport.ErrCorruptedPacket
+			return nil, errors.New("Socks|UDP: Insufficient length of packet.")
 		}
 		ip := packet[4:8]
 		request.Port = v2net.PortFromBytes(packet[8:10])
@@ -61,7 +59,7 @@ func ReadUDPRequest(packet []byte) (*Socks5UDPRequest, error) {
 		dataBegin = 10
 	case AddrTypeIPv6:
 		if len(packet) < 22 {
-			return nil, transport.ErrCorruptedPacket
+			return nil, errors.New("Socks|UDP: Insufficient length of packet.")
 		}
 		ip := packet[4:20]
 		request.Port = v2net.PortFromBytes(packet[20:22])
@@ -70,15 +68,14 @@ func ReadUDPRequest(packet []byte) (*Socks5UDPRequest, error) {
 	case AddrTypeDomain:
 		domainLength := int(packet[4])
 		if len(packet) < 5+domainLength+2 {
-			return nil, transport.ErrCorruptedPacket
+			return nil, errors.New("Socks|UDP: Insufficient length of packet.")
 		}
 		domain := string(packet[5 : 5+domainLength])
 		request.Port = v2net.PortFromBytes(packet[5+domainLength : 5+domainLength+2])
 		request.Address = v2net.ParseAddress(domain)
 		dataBegin = 5 + domainLength + 2
 	default:
-		log.Warning("Unknown address type ", addrType)
-		return nil, ErrorUnknownAddressType
+		return nil, fmt.Errorf("Socks|UDP: Unknown address type %d", addrType)
 	}
 
 	if len(packet) > dataBegin {
diff --git a/proxy/socks/protocol/udp_test.go b/proxy/socks/protocol/udp_test.go
index 2e523934..60f0d2c2 100644
--- a/proxy/socks/protocol/udp_test.go
+++ b/proxy/socks/protocol/udp_test.go
@@ -5,7 +5,6 @@ import (
 
 	v2net "v2ray.com/core/common/net"
 	"v2ray.com/core/testing/assert"
-	"v2ray.com/core/transport"
 )
 
 func TestSingleByteUDPRequest(t *testing.T) {
@@ -15,7 +14,7 @@ func TestSingleByteUDPRequest(t *testing.T) {
 	if request != nil {
 		t.Fail()
 	}
-	assert.Error(err).Equals(transport.ErrCorruptedPacket)
+	assert.Error(err).IsNotNil()
 }
 
 func TestDomainAddressRequest(t *testing.T) {
diff --git a/proxy/vmess/encoding/client.go b/proxy/vmess/encoding/client.go
index de862241..5c50febd 100644
--- a/proxy/vmess/encoding/client.go
+++ b/proxy/vmess/encoding/client.go
@@ -3,15 +3,14 @@ package encoding
 import (
 	"crypto/md5"
 	"crypto/rand"
+	"fmt"
 	"hash/fnv"
 	"io"
-
 	"v2ray.com/core/common/crypto"
 	"v2ray.com/core/common/log"
 	v2net "v2ray.com/core/common/net"
 	"v2ray.com/core/common/protocol"
 	"v2ray.com/core/proxy/vmess"
-	"v2ray.com/core/transport"
 )
 
 func hashTimestamp(t protocol.Timestamp) []byte {
@@ -113,8 +112,7 @@ func (this *ClientSession) DecodeResponseHeader(reader io.Reader) (*protocol.Res
 	}
 
 	if buffer[0] != this.responseHeader {
-		log.Info("Raw: Unexpected response header. Expecting ", this.responseHeader, " but actually ", buffer[0])
-		return nil, transport.ErrCorruptedPacket
+		return nil, fmt.Errorf("VMess|Client: Unexpected response header. Expecting %d but actually %d", this.responseHeader, buffer[0])
 	}
 
 	header := &protocol.ResponseHeader{
diff --git a/proxy/vmess/encoding/commands.go b/proxy/vmess/encoding/commands.go
index bf72c3e5..ae79d8be 100644
--- a/proxy/vmess/encoding/commands.go
+++ b/proxy/vmess/encoding/commands.go
@@ -9,7 +9,6 @@ import (
 	"v2ray.com/core/common/protocol"
 	"v2ray.com/core/common/serial"
 	"v2ray.com/core/common/uuid"
-	"v2ray.com/core/transport"
 )
 
 var (
@@ -54,12 +53,12 @@ func MarshalCommand(command interface{}, writer io.Writer) error {
 
 func UnmarshalCommand(cmdId byte, data []byte) (protocol.ResponseCommand, error) {
 	if len(data) <= 4 {
-		return nil, transport.ErrCorruptedPacket
+		return nil, errors.New("VMess|Command: Insufficient length.")
 	}
 	expectedAuth := Authenticate(data[4:])
 	actualAuth := serial.BytesToUint32(data[:4])
 	if expectedAuth != actualAuth {
-		return nil, transport.ErrCorruptedPacket
+		return nil, errors.New("VMess|Command: Invalid auth.")
 	}
 
 	var factory CommandFactory
@@ -111,38 +110,38 @@ func (this *CommandSwitchAccountFactory) Marshal(command interface{}, writer io.
 func (this *CommandSwitchAccountFactory) Unmarshal(data []byte) (interface{}, error) {
 	cmd := new(protocol.CommandSwitchAccount)
 	if len(data) == 0 {
-		return nil, transport.ErrCorruptedPacket
+		return nil, errors.New("VMess|SwitchAccountCommand: Insufficient length.")
 	}
 	lenHost := int(data[0])
 	if len(data) < lenHost+1 {
-		return nil, transport.ErrCorruptedPacket
+		return nil, errors.New("VMess|SwitchAccountCommand: Insufficient length.")
 	}
 	if lenHost > 0 {
 		cmd.Host = v2net.ParseAddress(string(data[1 : 1+lenHost]))
 	}
 	portStart := 1 + lenHost
 	if len(data) < portStart+2 {
-		return nil, transport.ErrCorruptedPacket
+		return nil, errors.New("VMess|SwitchAccountCommand: Insufficient length.")
 	}
 	cmd.Port = v2net.PortFromBytes(data[portStart : portStart+2])
 	idStart := portStart + 2
 	if len(data) < idStart+16 {
-		return nil, transport.ErrCorruptedPacket
+		return nil, errors.New("VMess|SwitchAccountCommand: Insufficient length.")
 	}
 	cmd.ID, _ = uuid.ParseBytes(data[idStart : idStart+16])
 	alterIdStart := idStart + 16
 	if len(data) < alterIdStart+2 {
-		return nil, transport.ErrCorruptedPacket
+		return nil, errors.New("VMess|SwitchAccountCommand: Insufficient length.")
 	}
 	cmd.AlterIds = serial.BytesToUint16(data[alterIdStart : alterIdStart+2])
 	levelStart := alterIdStart + 2
 	if len(data) < levelStart+1 {
-		return nil, transport.ErrCorruptedPacket
+		return nil, errors.New("VMess|SwitchAccountCommand: Insufficient length.")
 	}
 	cmd.Level = uint32(data[levelStart])
 	timeStart := levelStart + 1
 	if len(data) < timeStart {
-		return nil, transport.ErrCorruptedPacket
+		return nil, errors.New("VMess|SwitchAccountCommand: Insufficient length.")
 	}
 	cmd.ValidMin = data[timeStart]
 	return cmd, nil
diff --git a/proxy/vmess/encoding/server.go b/proxy/vmess/encoding/server.go
index 5ed7e311..33973268 100644
--- a/proxy/vmess/encoding/server.go
+++ b/proxy/vmess/encoding/server.go
@@ -2,16 +2,15 @@ package encoding
 
 import (
 	"crypto/md5"
+	"errors"
 	"hash/fnv"
 	"io"
-
 	"v2ray.com/core/common/crypto"
 	"v2ray.com/core/common/log"
 	v2net "v2ray.com/core/common/net"
 	"v2ray.com/core/common/protocol"
 	"v2ray.com/core/common/serial"
 	"v2ray.com/core/proxy/vmess"
-	"v2ray.com/core/transport"
 )
 
 type ServerSession struct {
@@ -61,8 +60,7 @@ func (this *ServerSession) DecodeRequestHeader(reader io.Reader) (*protocol.Requ
 	iv := timestampHash.Sum(nil)
 	account, err := user.GetTypedAccount()
 	if err != nil {
-		log.Error("Vmess: Failed to get user account: ", err)
-		return nil, err
+		return nil, errors.New("VMess|Server: Failed to get user account: " + err.Error())
 	}
 
 	aesStream := crypto.NewAesDecryptionStream(account.(*vmess.InternalAccount).ID.CmdKey(), iv)
@@ -70,8 +68,7 @@ func (this *ServerSession) DecodeRequestHeader(reader io.Reader) (*protocol.Requ
 
 	nBytes, err := io.ReadFull(decryptor, buffer[:41])
 	if err != nil {
-		log.Debug("Raw: Failed to read request header (", nBytes, " bytes): ", err)
-		return nil, err
+		return nil, errors.New("VMess|Server: Failed to read request header: " + err.Error())
 	}
 	bufferLen := nBytes
 
@@ -81,7 +78,7 @@ func (this *ServerSession) DecodeRequestHeader(reader io.Reader) (*protocol.Requ
 	}
 
 	if request.Version != Version {
-		log.Info("Raw: Invalid protocol version ", request.Version)
+		log.Info("VMess|Server: Invalid protocol version ", request.Version)
 		return nil, protocol.ErrInvalidVersion
 	}
 
@@ -98,32 +95,28 @@ func (this *ServerSession) DecodeRequestHeader(reader io.Reader) (*protocol.Requ
 		nBytes, err = io.ReadFull(decryptor, buffer[41:45]) // 4 bytes
 		bufferLen += 4
 		if err != nil {
-			log.Debug("VMess: Failed to read target IPv4 (", nBytes, " bytes): ", err)
-			return nil, err
+			return nil, errors.New("VMess|Server: Failed to read IPv4: " + err.Error())
 		}
 		request.Address = v2net.IPAddress(buffer[41:45])
 	case AddrTypeIPv6:
 		nBytes, err = io.ReadFull(decryptor, buffer[41:57]) // 16 bytes
 		bufferLen += 16
 		if err != nil {
-			log.Debug("VMess: Failed to read target IPv6 (", nBytes, " bytes): ", nBytes, err)
-			return nil, err
+			return nil, errors.New("VMess|Server: Failed to read IPv6 address: " + err.Error())
 		}
 		request.Address = v2net.IPAddress(buffer[41:57])
 	case AddrTypeDomain:
-		nBytes, err = io.ReadFull(decryptor, buffer[41:42])
+		_, err = io.ReadFull(decryptor, buffer[41:42])
 		if err != nil {
-			log.Debug("VMess: Failed to read target domain (", nBytes, " bytes): ", nBytes, err)
-			return nil, err
+			return nil, errors.New("VMess:Server: Failed to read domain: " + err.Error())
 		}
 		domainLength := int(buffer[41])
 		if domainLength == 0 {
-			return nil, transport.ErrCorruptedPacket
+			return nil, errors.New("VMess|Server: Zero domain length.")
 		}
 		nBytes, err = io.ReadFull(decryptor, buffer[42:42+domainLength])
 		if err != nil {
-			log.Debug("VMess: Failed to read target domain (", nBytes, " bytes): ", nBytes, err)
-			return nil, err
+			return nil, errors.New("VMess|Server: Failed to read domain: " + err.Error())
 		}
 		bufferLen += 1 + domainLength
 		request.Address = v2net.DomainAddress(string(buffer[42 : 42+domainLength]))
@@ -131,8 +124,7 @@ func (this *ServerSession) DecodeRequestHeader(reader io.Reader) (*protocol.Requ
 
 	nBytes, err = io.ReadFull(decryptor, buffer[bufferLen:bufferLen+4])
 	if err != nil {
-		log.Debug("VMess: Failed to read checksum (", nBytes, " bytes): ", nBytes, err)
-		return nil, err
+		return nil, errors.New("VMess|Server: Failed to read checksum: " + err.Error())
 	}
 
 	fnv1a := fnv.New32a()
@@ -141,7 +133,7 @@ func (this *ServerSession) DecodeRequestHeader(reader io.Reader) (*protocol.Requ
 	expectedHash := serial.BytesToUint32(buffer[bufferLen : bufferLen+4])
 
 	if actualHash != expectedHash {
-		return nil, transport.ErrCorruptedPacket
+		return nil, errors.New("VMess|Server: Invalid auth.")
 	}
 
 	return request, nil
diff --git a/proxy/vmess/io/reader.go b/proxy/vmess/io/reader.go
index 6b5bd9c2..4eeb36bb 100644
--- a/proxy/vmess/io/reader.go
+++ b/proxy/vmess/io/reader.go
@@ -1,13 +1,12 @@
 package io
 
 import (
+	"errors"
 	"hash"
 	"hash/fnv"
 	"io"
-
 	"v2ray.com/core/common/alloc"
 	"v2ray.com/core/common/serial"
-	"v2ray.com/core/transport"
 )
 
 // Private: Visible for testing.
@@ -93,7 +92,7 @@ func (this *AuthChunkReader) Read() (*alloc.Buffer, error) {
 		this.validator.Consume(buffer.Value[:this.chunkLength])
 		if !this.validator.Validate() {
 			buffer.Release()
-			return nil, transport.ErrCorruptedPacket
+			return nil, errors.New("VMess|AuthChunkReader: Invalid auth.")
 		}
 		leftLength := buffer.Len() - this.chunkLength
 		if leftLength > 0 {
diff --git a/transport/errors.go b/transport/errors.go
deleted file mode 100644
index a76e93c9..00000000
--- a/transport/errors.go
+++ /dev/null
@@ -1,9 +0,0 @@
-package transport
-
-import (
-	"errors"
-)
-
-var (
-	ErrCorruptedPacket = errors.New("Packet is corrupted.")
-)